login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A170826 a(n) = gcd(n^2, n!). 5
1, 2, 3, 8, 5, 36, 7, 64, 81, 100, 11, 144, 13, 196, 225, 256, 17, 324, 19, 400, 441, 484, 23, 576, 625, 676, 729, 784, 29, 900, 31, 1024, 1089, 1156, 1225, 1296, 37, 1444, 1521, 1600, 41, 1764, 43, 1936, 2025, 2116, 47, 2304, 2401, 2500, 2601, 2704, 53, 2916 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..54.

FORMULA

If n is prime then a(n) = n; otherwise, if n <> 4 then a(n) = n^2. - Zak Seidov, Dec 28 2009

a(n) = n!/A092043(n). - Johannes W. Meijer, Jun 04 2016

MAPLE

GCDWITHFACTORIAL:=proc(a) local b, i, k:

if whattype(a) <> list then RETURN([]); fi:

b:=[]:

for i to nops(a) do b:=[op(b), gcd(a[i], i!)]: od;

RETURN(b);

end:

A170826 := proc(n): gcd(n^2, n!) end: seq(A170826(n), n=1..54); # Johannes W. Meijer, Jun 04 2016

MATHEMATICA

Table[GCD[n^2, n!], {n, 54}] (* Michael De Vlieger, Jun 05 2016 *)

PROG

(PARI) a(n)=if(isprime(n), n, if(n==4, 8, n^2)) \\ Charles R Greathouse IV, Feb 01 2013

CROSSREFS

Cf. A092043.

Sequence in context: A184392 A007955 A324502 * A162537 A109844 A128779

Adjacent sequences: A170823 A170824 A170825 * A170827 A170828 A170829

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Dec 27 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 9 23:05 EST 2022. Contains 358710 sequences. (Running on oeis4.)